448 
.1. GRAY. 
■ Until immediately after the dissolution of the nuclear 
membrane in the first segmentation division the behaviour is 
normal, and thirty-eight normal chromosomes can be counted. 
As the spindle is formed, the chromosomes become scattered 
upon it irregularly, and gradually become collected in the 
ecjuatorial plate. During this process it is seen that a con- 
siderable though variable number of them are either swollen 
up, or more commonly bear vesicles attached to their ends 
or sides. The staining of the vesicles is always less intense 
than that of the clu'omosomes, and is progressively fainter 
the more the vesicle is developed, so giving the impression 
that the chromosome has swollen at one point, and that the 
chromatin is thus more thinly diffused in the wall of the 
vesicle than in the normal part of the chromosome. In the 
equatorial plate stage the vesicles may either remain attached 
to the chromosomes which produced them, or become 
separated from them; those which become separated tend to 
take up positions round the edge of the equatorial plate, 
sometimes outside the spindle. The normal chromosomes and 
those of which the normal shape has not become much altered 
by vesicle production then split longitudinally in the ordinary 
way, and begin to travel to the poles. It may sometimes l>e 
seen that a chromosome with a vesicle attached has split, ami 
the vesicle, remaining attached to one half, is being carried 
with it towards the pole. It is possible that a few chromo- 
somes, the greater part of which has become swollen into a 
vesicle, do not divide, but are carried entire to one or other 
pole. The vesicles which have become separated from their 
parent chromosomes appear to differ in their fate according 
to their position. If they lie among the chromosomes inside 
the spindle, they are carried with them to one or other pole 
and become included in the daughter-nuclei. If, however, 
they are left on the edge of the spindle, as commonly happens 
with the larger vesicles, they remain outside the mitotic 
figure in the cytoplasm, and are not included in the nuclei of 
the daughter-cells. In tin’s case they usually contract and 
become sjnall evenly stained spheres, not easily distinguish- 
